From The Trenches
One of the most common service problems is the maladjustment of the detector high voltage setting. We receive many calls from users who have attempted to trouble-shoot their instrument with a "high Impedance" voltmeter. This usually results with the problem of not being able to adjust the high voltage above 450 V. The reason for this problem is the "high impedance" voltmeter typically has an 11 MΩ output impedance and will overload on resistive loads below 60 MΩ. Read more here!